On 7/18/11 5:26 PM, Mark Thorson wrote:> It could be argued that the National Semiconductor NS16032 (later> renamed NS32016) qualifies. The designers Les Kohn and Dan O'Dowd> started with an instruction set more-or-less based on the VAX and> pared it down to what they considered a minimum. Dan wrote a Pascal> compiler that guided the design of the architecture in the sense that> every time the chip designers in Israel asked whether they could> delete a feature Les would turn to Dan and ask how that would affect> the compiler. That chip was intended to be a general-purpose> architecture, but the compiler guided decisions on what features were> important.>> Four instructions were deleted relatively late in the design process,> and you can see the places where they would have been if you look at> any early 32000 family die. There are four clear stripes that span> the microcode ROM. I believe these are visible on all 32000 family> devices through the NS32332. If I remember correctly, the CPU was> reimplemented in the NS32532, at which point the stripes disappeared.>> [Too bad they didn't have time to debug the chip before they shipped> it. The NS chips, at least the early ones, were so buggy as to be> almost unusable. -John]

Yes, I was very interested in the instruction descriptions for the
NS32016. Seems it had a "CASE" assembly language instruction.
But I heard that the chip had hardware problems that were *never*
worked out... Too bad.